At present, during assembling and producing yaw apparatus by major wind power generating manufacturers, tightening tools, such as pneumatic impact wrench and hydraulic wrench, are generally used to tighten bolts on the yaw apparatus during bolt-tightening process. However, this kind of tightening tools has disadvantages including noise, vibration, inconvenient operation, high human cost, incapableness of ensuring the torque precision of the tightened bolt and deformation of yaw members; most importantly, the assembling quality is hard to be ensured. For example, with regard to the noise, the noise of the pneumatic impact wrench is more than 90 DB, and the noise of the hydraulic wrench is more than 80 DB; with regard to the torque precision, the torque error of the pneumatic impact wrench is about 30%, and the torque error of the pneumatic impact wrench is about 20%.